Structural beam



Oct. 27, 1936.

w. H. WEISKOPF ET AL STRUCTURAL BEAM Filed March 16, 1935 Patented Oct. 27, 1936 UNITED STATES STRUCTURAL BEAM Walter H. Weiskopf, New Rochelle, and John W. Pickworth, Bronxville, N. Y.

Application March 16, 1933, Serial No. 660,998

5 Claims.

Our present invention relates generally to steel structures, and has particular reference to a new and improved type of structural beam.

It is a general object of our invention to provide a beam of the plate girder variety, designed primarily for railroad or highway use, as, for example, in the construction of over-passes, bridges, and the like.

The principal features of our present beam lie in the provision of a so-called clear flange, and in an arrangement of parts which results in greater economy of material and workmanship. A beam constructed in accordance with our present invention is of particular utility wherever there are no restrictive requirements as to depth.

Our present beam is of the general character which includes two opposite flanges and an intermediate web, and is characterized by a sectional construction of compression flange and/or web, whereby the requirements imposed by the bending moments and shearing stresses (varying from point to point longitudinally along the beam) may be met with greater efliciency. More particularly, it is a feature of our invention to provide a compression flange which consists of at least two flange members arranged end to end, each of the members being of T cross-section with the stem of the T integral with the crossbar thereof. Similarly, it is a feature of our invention to provide a web which is composed of at least two web plates arranged end toend. In accordance with our invention, each T-shaped flange member is of heavier construction than that of the adjacent flange member in the region of lesser bending moment; and, similarly, the web plate in the region of lesser shearing stresses is of less thickness than the adjacent plate or plates in the region or regions of greater shearing stresses.

The provision of a structural beam with the compression flange composed of a series of members of T-shaped cross-section is an important feature which lies at the basis of the accomplishment of a number of advantages. It permits the outer surfaces of the cross-bars of the Ts to be arranged in flush relationship, so that the resultant beam has a clear flange, devoid of rivet heads, cover plates, and other irregularities. It also permits us to provide a web of varying thickness, without requiring any crimping of flanges or other similar adjustments or manipulations of an inefficient or unsafe character.

One of the features of our construction lies in arranging the adjacent T-shaped flange members of the compression flange with one set of side surfaces of the T stems in flush relationship. This permits the web plate or plates to be connected to these stems along the flush sides thereof; and, furthermore, it permits a series of separate web plates tobe employed, having difierent thicknesses, by merely arranging the web plates with one set of side surfaces thereof in flush relationship.

Our beam is further characterized by a tension flange composed essentially of a T-shaped flange member with the stem of the T integral with the cross-bar, the additional flange area required in the region or regions of greater bending moment being provided by means of auxiliary flange members of the T. Where the web is sectional, with one or more sections thinner than other adjacent sections, the auxiliary flange members of the tension flange are made of a shorter length than the corresponding web plate or plates. Accordingly, these auxiliary flange members are not required to be crimped or adjusted in any inefficient or cumbersome manner.

We achieve the foregoing objects, and such other objects as may hereinafter appear or be pointed out, in the manner illustratively exemplified in the accompanying drawing, wherein Figure 1 is an elevational view of a beam constructed in accordance with our present invention, showing a little more than one-half of the beam;

Figure 2 is an enlarged fragmentary cross-sectional View taken substantially along the line 22 of Figure 1;

Figure 3 is an enlarged cross-sectional View taken substantially along the line 3--3 of Figure 1;

Figure 4 is an enlarged cross-sectional view taken substantially along the line 44 of Figure 1;

Figure 5 is a fragmentary cross-sectional view taken substantially along the line 5-5 of Figure 1; and

Figure 6 is a fragmentary cross-sectional view taken substantially along the line 6-6 of Figure 1.

In the beam illustrated in Figure 1, by way of example, the reference numeral I6 designates one end of the beam, and the reference numeral H is applied to approximately what is the center of the beam, it being understood that in the average construction the other half of the beam will be the reverse counterpart of the portion shown.

In the embodiment illustrated, the compression flange consists of three sections, the centralflange member I2 being arranged in endwise alignment with two outer flange members, the left-hand member I3 being shown in Figure 1.

Each of these flange members is of T-shaped cross-section, with the stem of the T integral with the cross-bar thereof. The contiguous abutting ends of these members are machined so that they may be arranged in successive 'end-to-end abutment. In accordance with our invention, the middle or center flange member I2 is of heavier construction than each of the outer members, to provide a greater flange area in the central region of the beam, where the bending moments are greater. is herein used and in the appended claims, it will be understood that we refer generally to any construction whereby a greater flange area isproduced.

For example, the cross-bar of the T may be thicker and wider, and/ or the stem may be thicker and/or longer. Upon referring to Figure 3, it will be observed that in the embodiment chosen for illustration we have shown the flange member I2 with a wider and slightly thicker cross-bar, and with a stem not only thicker but slightly longer than the stem ofthe sections I3.

In accordance with our invention, the members I2 and I3 (and the member I2 and the corresponding right-hand flange member), are arranged with the outer surfaces M of the crossbars of the Ts in flush relationship. This provides for an entirely clear flange throughout the entire length of the beam. At the same time, we arrange one set of side surfaces of the T stems in flush relationship, and upon viewing Figures 2 and 3 it will be observed that the side surface I5 of the stem of the member I3 is arranged in flush relationship with the side surface I6 of the stem of the flange'member I2.

The tension flange of the present beam is composed of a single flange member II which is preferably of T-shaped cross-section with the stem of the T integral with the cross-bar. At'the midportion of the beam, additional flange area is provided by the arrangement of the auxiliary flange members I8 secured to the stem of the member I? and the web plates I9 and 20. In the form herein illustrated, these auxiliary members are provided by two opposite angle members.

The present beam is completed by means of a web which extends from the compression flange to the tension flange. Our present construction provides for attaching the web to the opposed stem portions of the opposite Ts. In the embodiment herein illustrated, the web is composed of four sections, two central sections I9 and 20, and two outer sections, one of which is designated by the reference numeral 2 I, and the other of which is similar to the plate 2| at the opposite end of the beam.

In accordance with our invention, the central plates l9 and 29 are thinner than the adjacent outer plates typified by the plate 2I, because the shearing stresses aregreater in the regions near the ends of the beam than they are in the central region or regions.

In Figures 2 and 5, it will be observed that the plate 2I is thicker than the plate I9, and it will be noted that these plates are arranged end to end, with one set of side surfaces in flush relationship. As viewed in Figure 2, the'side surfaces which are uppermost are arranged flush with each other, and as viewed in Figure 5' the side surfaces which face toward the bottom of the figure are flush. It is these flush surfaces which are brought into contact with the flush side By the term heavier, as the same 5 surfaces of the T stems of the members I2 and It will be observed that the line along which the plates I9 and 2| are arranged end to end does not necessarily coincide with the line along which the members I2 and I3 are abutted. If desired, these lines may coincide at a selected point along the longitudinal length of the beam, but it is often preferable to extend the web plate 2I further toward the center of the beam than the flange member I3. The arrangement of the flange members I2 and I3, with one set of side surfaces of the T stems in flush relationship, permits the web plates to be made of any convenient lengths, without requiring either of these web plates to be cr'imped.

It is also to be observed that the auxiliary flange members I8 are of shorter length than the central sections I9 and 20 of the web. In other words, the left end 22 of the members I8 terminates nearer the center of the beam than the left end of the plate l9, as shown most clearly in Figure 5. This permits the auxiliary members I8 to be attached without requiring any crimping thereof due to change of thickness of web.

The manner in which the several parts are attached together has not been fully illustrated, but will be readily understood by those skilled in the art. Merely by way of illustration, we have shown a pair of splicing plates 23 and 24 along the line of juncture of the web plates I9 and 2|. A filler plate 25 may be conveniently arranged under the splice plate 23 where the latter overlaps the thinner web plate I9.

A similar set of splice plates 26 and 21 have been shown along the line of abutment of the web plates I9 and 20, but since these two web plates are of the same thickness no filler plate is necessary at this point.

It will be understood that if the length of the beam permits, the central section of the web may be a single plate and need not necessarily be composed of the two web plates I9 and 20 spliced as at 26 and 21.

It will also be understood that splice plates or the like are arranged in any convenient or desired manner along the lines of juncture of the several aligned sections of the compression flange; and it should be noted that splicing is required only along the stems of the Ts, thereby leaving the outer upper surface of the beam, smooth and free of rivet heads and the like.

Web stiifeners 28 may be conveniently arranged at predetermined points, in accordance with requirements; and wherever possible these stiffeners extend all the way to the cross-bars of the Ts at the opposite sides of the beam. At the midportion of the beam, where the auxiliary flange members I8 are arranged, the web stiffeners may be conveniently terminated at these members, as illustrated most clearly in Figures 1 and 4. Some of the stiffeners may have to be crimped, as illustrated in Figures 3 and 4, but this is a common expedient that can be resorted to where desired. If desired, such crimping of web stiifeners may be obviated by providing flller pieces where necessary. Crimping of web stiffeners is perfectly safe and common practice, but crimping of flanges, which our invention obviates, is unsafe since the flanges carry vital direct stresses.

We have not illustrated the method of fastening the several parts to each other in the drawing for the reason that the arrangement of rivets or weldsto hold the several parts together is an obvious matter which will be readily understood by those skilled in the art, from the description given. It should be noted, however, that no rivets or rivet holes are necessary in the cross-bars of the T-shaped flange members. This simplifies the work of assembly in the shop, and efiects an obvious economy in material.

It will also be understood that the number of sections into which the compression flange and/or the web may be divided is a matter depending upon the desires and requirements of the designer. In the usual beam, three sections provide a highly eflicient and economical structure, although, obviously, more than three sections may be provided if desired. In fact, the construction illustrated shows the web composed of four sections, but the two central sections are merely continuations of one another, so far as thickness is concerned.

The advantages of the present construction lie not only in the provision of a clear flange, but also in a marked economy of material and workmanship. The clear flange makes the present beam particularly useful in connection with railroad bridges, since railroad ties may be conveniently mounted upon the upper surfaces of two parallel beams of the present character without requiring any notching of the ties to compensate for rivet heads or irregularities provided by cover plates. While we have shown a construction in which the outer surface of the tension flange is also smooth and uninterrupted, it will be understood that a clear flange at the bottom, though advantageous, is not as important as a clear flange at the top.

It is the T-shaped nature of the flanges which permits the Web to be composed of separate sections having different thicknesses; and it may be noted in passing that the conventional plate girder (composed of a web, four angles, and two or more cover plates), is uniformly provided with a web of uniform thickness throughout, because a variation in thickness would be unfeasible because of the impracticability of crimping the flange angles. This uniform thickness is computed on the basis of the minimum thickness permissible at the region of greatest shearing stress, which is at the end of the beam. This means that the conventional plate girder has a web thickness at the midportion which is greater than necessary. In accordance with our present invention, however, a beam may be provided in which the web thickness may conform, more efficiently, to the shear diagram, i. e. to the reduced thickness which the lesser shear stresses at the center of the beam permit.

From certain aspects, it will be understood that a web of uniform thickness throughout may be employed in a beam of the present character, while the advantages accruing from the sectional nature of the compression flange may still be retained. Similarly, in certain beams, the compression flange may be composed of a single member uniform in cross-section throughout the length of the beam, while the web may be caused to vary in thickness in the manner herein illustrated and described. Furthemore, while we have shown the central compression flange member with a thicker and wider cross-bar and a thicker and longer T stem, the additional area may in many cases be provided by increasing only one or several of these dimensions. The important feature lies in the fact that the outer surfaces of the cross-bar are flush with one another, and that the side surfaces of the T stems are flush with one another on one side.

In general, it will be understood that changes in the details herein described and illustrated for the purpose of explaining the nature of our invention may be made by those skilled in the art without departing from the spirit and scope of the invention as expressed in the appended claims. It is therefore intended that these details be interpreted as illustrative, and not in a limiting sense.

Having thus described our invention, and illustrated its use, what we claim as new and desire to secure by Letters Patent is- 1. In a structural beam having two opposite flanges and an intermediate web, a compression flange comprising at least two flange members arranged end to end, each member being of T-shaped cross-section with the stem integral with the cross-bar of the T, the member in the region of greater bending moment being heavier than the adjacent member in the region of lesser bending moment, said members being arranged with one set of side surfaces of the T stems in flush relationship, and said web comprising a plate connected to said T stems along the flush sides thereof.

2. In a structural beam having two opposite flanges and an intermediate web, a compression flange comprising at least two flange members arranged end to end, each member being of T-shape cross-section with the stem integral with the cross-bar of the T, the member in the region of greater bending moment being heavier than the adjacent member in the region of lesser bending moment, said members being arranged with the outer surfaces of the T crossbars and with one set of side surfaces of the T stems in flush relationship, and said web comprising a plate connected to said T stems along the flush sides thereof.

3. In a structural beam, a compression flange comprising at least two flange members arranged end to end, each member being of T-shaped cross-section with the stem integral with the cross-bar of the T, the member in the region of greater bending moment being heavier than the adjacent member in the region of lesser bending moment, said members being arranged with one set of side surfaces of the T stems in flush relationship, and a web comprising at least two web plates arranged end to end and secured to the flush sides of said T stems, the plate in the region of greater shearing stress being thicker than the adjacent plate in the region of lesser shearing stress, the inner set of side surfaces of said plates being in flush relationship.

4. In a structural beam, a compression flange, a tension flange, and an intermediate web; the compression flange comprising at least two flange members arranged end to end, each member being of T-shaped cross-section with the stem integral with the cross-bar of the T, the member in the region of greater bending moment being heavier than the adjacent member in the region of lesser bending moment, said members being arranged with the outer surfaces of the T cross-bars and with one set of side surfaces of the T stems in flush relationship; the tension flange also comprising a member of T-shaped cross-section with the stem integral with the cross-bar of the T, auxiliary flange members secured to the last-named T stem and to the web in the region of greater bending moment; and the web comprising at least two web plates arranged end to end and. secured to said T stems along the. flush sides thereof, the plate in the region of greater shearing stress being thicker than the adjacent plate in the region of lesser shearing stress.

5.v In a structural beam, a compression flange comprising three flange members arranged end to end, each member being of T-shaped crosssection with the stem integral with the cross-bar of the T, the center member being heavier than the outer members, said members being arranged with the outer surfaces of the T cross-bars and with one set of side surfaces of the T stems in flush relationship, a tensionflange comprising a single member of T-shaped cross-section'with the stem integral with the cross-bar of the T, auxiliary flange members secured to the midportion of the tension flange along the T stem thereof, and a Web comprising three web plates arranged end to end and secured to said T stems along the flush sides of the latter, the center plate being thinner than the others, and longer than said auxiliary flange members.

WALTER H. WEISKOPF. JOHN W. PICKWORTH. 

